tp: fix stack OOB write in ParseChromeEvents Chrome metadata key#5586
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ParseChromeEvents built a "cr-[<index>-]<name>" key for each ChromeMetadata entry into a fixed 2048-byte stack buffer via FixedStringWriter, whose only bounds check is PERFETTO_DCHECK (a no-op in release). Since metadata.name() is an attacker-controllable string from the trace, an oversized name causes an out-of-bounds memcpy past the buffer, corrupting adjacent stack state (e.g. the ArgsTracker declared earlier in the function) before the stack canary is checked. Build the key into a std::string instead. Not a hot path (a handful of metadata entries per trace), so the heap allocation is negligible.
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sashwinbalaji
approved these changes
Apr 25, 2026
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ParseChromeEvents built a "cr-[-]" key for each
ChromeMetadata entry into a fixed 2048-byte stack buffer via
FixedStringWriter, whose only bounds check is PERFETTO_DCHECK (a no-op
in release). Since metadata.name() can theoretically be arbitrary size,
an oversized name causes an out-of-bounds memcpy past
the buffer, corrupting adjacent stack state (e.g. the ArgsTracker
declared earlier in the function) before the stack canary is checked.
Build the key into a std::string instead. Not a hot path (a handful of
metadata entries per trace), so the heap allocation is negligible.